The inflammatory response is complex and is mediated by a variety of signaling molecules produced locally by mast cells, nerve endings, platelets, leucocytes and complement activation. Certain of these signaling molecules cause the endothelial cell lining to become more porous and/or even to express selectins which act as cell surface molecules which recognize and attract leucocytes through specific carbohydrate recognition. Stronger leucocyte binding is mediated by integrins, which mediate leukocyte movement through the endothelium. Additional signaling molecules act as chemoattractants, causing the bound leucocytes to crawl towards the source of the attractant. Other signaling molecules produced in the course of an inflammatory response escape into the blood and stimulate the bone marrow to produce more leucocytes and release them into the blood stream.
Inflammation is typically initiated by an antigen, which can be virtually any molecule capable of initiating an immune response. Under normal physiological conditions these are foreign molecules, but molecules generated by the organism itself can serve as the catalyst as is known to occur in various disease states.
T-cell proliferation in a mixed lymphocyte culture or mixed lymphocyte reaction (MLR) is an established indication of the ability of a compound to stimulate the immune system. In an inflammatory response, the responding leucocytes can be neutrophilic, eosinophilic, monocytic or lymphocytic. Histological examination of the affected tissues provides evidence of an immune stimulating or inhibiting response. See Current Protocols in Immunology, ed. John E. Coligan, 1994, John Wiley and Sons, Inc.
Inflammatory bowel disease (IBD) is a term used to collectively describe gut disorders including both ulcerative colitis (UC) and Crohn's disease, both of which are classified as distinct disorders, but share common features and likely share pathology. The commonality of the diagnostic criteria can make it difficult to precisely determine which of the two disorders a patients has; however the type and location of the lesion in each are typically different. UC lesions are characteristically a superficial ulcer of the mucosa and appear in the colon, proximal to the rectum. CD lesions are characteristically extensive linear fissures, and can appear anywhere in the bowel, occasionally involving the stomach, esophagus and duodenum.
Conventional treatments for IBD usually involve the administration of antiinflammatory or immunosuppressive agents, such as sulfasalazine, corticosteroids, 6-mercaptopurine/azathoprine, or cyclosporine all of which only bring partial relief to the afflicted patient. However when antiinflammatory/immunosuppresive therapies fail, colectomies are the last line of defense. Surgery is required for about 30% of CD patients within the first year after diagnosis, with the likelihood for operative procedure increasing about 5% annually thereafter. Unfortunately, CD also has a high rate of reoccurrence as about 5% of patients require subsequent surgery after the initial year. UC patients further have a substantially increased risk of developing colorectal cancer. Presumably this is due to the recurrent cycles of injury to the epithelium, followed by regrowth, which continually increases the risk of neoplastic transformation.
A recently discovered member of the immunoglobulin superfamily known as Junctional Adhesion Molecule (JAM) has been identified to be selectively concentrated at intercellular junctions of endothelial and epithelial cells of different origins. Martin-Padura, I. et al., J. Cell Biol. 142(1): 117-27 (1998). JAM is a type I integral membrane protein with two extracellular, intrachain disulfide loops of the V-type. JAM bears substantial homology to A33 antigen (FIG. 1 or FIG. 18). A monoclonal antibody directed to JAM was found to inhibit spontaneous and chemokine-induced monocyte transmigration through an endothelial cell monolayer in vitro. Martin-Padura, supra
It has been recently discovered that JAM expression is increased in the colon of CRF2-4 −/− mice with colitis. CRF 2-4 −/− (IL-10R subunit knockout mice) develop a spontaneous colitis mediated by lymphocytes, monocytes and neutrophils. Several of the animals also developed colon adenocarcinoma. As a result, it is foreseeable likely that the compounds of the invention are expressed in elevated levels in or otherwise associated with human diseases such as inflammatory bowel disease, other inflammatory diseases of the gut as well as colorectal carcinoma.
The compounds of the invention also bear significant homology to A33 antigen, a known colorectal cancer-associated marker. The A33 antigen is expressed in more than 90% of primary or metastatic colon cancers as well as normal colon epithelium. In carcinomas originating from the colonic mucosa, the A33 antigen is expressed homogeneously in more than 95% of all cases. The A33 antigen, however, has not been detected in a wide range of other normal tissues, i.e., its expression appears to be organ specific. Therefore, the A33 antigen appears to play an important role in the induction of colorectal cancer.
Since colon cancer is a widespread disease, early diagnosis and treatment is an important medical goal. Diagnosis and treatment of colon cancer can be implemented using monoclonal antibodies (mAbs) specific therefore having fluorescent, nuclear magnetic or radioactive tags. Radioactive gene, toxins and/or drug tagged mAbs can be used for treatment in situ with minimal patient description. mAbs can also be used to diagnose during the diagnosis and treatment of colon cancers. For example, when the serum levels of the A33 antigen are elevated in a patient, a drop of the levels after surgery would indicate the tumor resection was successful. On the other hand, a subsequent rise in serum A33 antigen levels after surgery would indicate that metastases of the original tumor may have formed or that new primary tumors may have appeared.
Such monoclonal antibodies can be used in lieu of, or in conjunction with surgery and/or other chemotherapies. For example, preclinical analysis and localization studies in patients infected with colorectal carcinoma with a mAb to A33 are described in Welt et al., J. Clin. Oncol. 8:1894-1906 (1990) and Welt et al., J. Clin. Oncol. 12:1561-1571 (1994), while U.S. Pat. No. 4,579,827 and U.S. Ser. No. 424,991 (E.P. 199,141) are direct to the therapeutic administration of monoclonal antibodies, the latter of which relates to the application of anti-A33 mAb.